1. Field of the Invention
The invention relates to a method and apparatus for topping off a line of moving containers with liquid and particularly to filling rapidly moving tilted containers from a continuously flowing source to an accurately determined headspace level, without any subsequent spillage while returning the topped up containers to an upright condition.
2. Background Art
U.S. Pat. No. 4,103,720, issued to B. C. EISENBERG on 1 Aug. 1978, describes a method and apparatus for filling open-top containers with liquid material. The containers are advanced continuously in a line along a predetermined path through a filing region where liquid material is discharged from a reservoir in a continuous sheet over an inclined plate, the lower edge of which extends in the direction of advance above the open tops of the line of containers. In the filling region, the containers are tilted transversely to the path at a predetermined angle with respect to the vertical, and the flow rate of the liquid is adjusted so that each container is overfilled as it passes through the filling region.
To prevent the liquid stream from contacting the external surface of the containers, thus avoiding an extra cleanup step after filling, streams of air are directed towards the tilted containers transversely to the line of advance below their tops, so that the air passes around the peripheries of the containers adjacent to their tops. The air flow laterally deflects any part of the sheet of liquid which would otherwise flow between adjacent containers and also deflects the liquid overflowing from the lower part of the open top of each tilted container away from the side of the container. The deflected liquid falls into a trough below the line of containers and is recirculated from the trough back to the reservoir.
In U.S. Pat. No. 4,349,053 issued 14 Sept. 1982, also to EISENBERG, an endless series of moving deflecting units, in the form of spaced deflecting wedges or successive funnels, replace the airstream of EISENBERG '720. The deflecting units pass under the discharge edge of the inclined plate in synchronism with the line of containers and divide the continuous liquid sheet flowing over the plate into individual moving streams directed into corresponding ones of the containers in the moving line.
The inventions in both the EISENBERG '720 and '053 patents are concerned with preventing any contact of the liquid of the continuous flowing stream with the outside surfaces of the containers to eliminate any need to clean the containers before they are sealed. For many liquid filling or topping off operations, this is not so important. For example, containers of many canned food products such as vegetables, olives, and so forth, pass through a briner after they have been filled with the food product. The briner adds premixed salt water, or fresh water which dissolves a salt tablet or granular salt in each container, up to a predetermined headspace level. In either case, the added liquid creates no cleanup problem if it splashes onto the outside surfaces of the containers.
Consequently, a conventional briner as manufactured by the assignee of the present application, is a simpler machine than those of the EISENBERG '720 and '053 patents. The liquid flows from an elongated trough through a longitudinal slot in the center of the bottom of the trough as a continuous sheet directly into a line of tilted containers moving in a straight line through the filling region. There are no deflector units moving with the containers and no ductwork for delivering a stream of air across the line of containers.
Both the conventional briner and the more sophisticated machines of the EISENBERG '720 and '053 patents have a common problem, however. Containers enter and leave these machines in an upright condition. In the machine they pass through an entry transition zone, where they are transversely tilted to a predetermined angle depending on the desired headspace level, then through a filling region, and finally through an exit transition zone, where they are returned to the upright condition. An endless chain conveyor transports the containers along the filling path at rates up to 500 containers per minute. Typically, the containers enter the briner in random fashion, and after filling with brine, they go into a timer feed screw to enter the next station, such as a seamer. Because of random feeding of the containers to the timing screw, the transfer into the screw is never smooth. Splashing occurs. If the liquid is not replaced, product quality will suffer.
Because of the need to synchronize the containers with the deflector units in the machine of EISENBERG '053, arms on an endless loop driven with the deflector units push the containers through the filling region and the transition zones. In this machine, an infeed timer screw delivers the containers to the pusher arms, and the arms in turn deliver the containers to an outfeed screw. As with the briner chain conveyor, the transfer to the outfeed timing screw is not smooth, particularly when the machine is operating at high feed rates in the 500 cpm, and above range. Consequently, some splashing after leaving the filling region occurs with the transport mechanisms of all of these liquid fillers.
Splashing not only results in out of tolerance headspace in a significant number of containers; it also creates an environmental problem. Since the return trough of these filling machines extends only to the end of the filling region, any spills in the outfeed transition zone will go to the floor, requiring drains to a disposal system or sewer.